Molded article transferring device and blow molding device

ABSTRACT

In an embodiment, an injection stretch blow molding device includes an injection molding section that produces N (N is an integer equal to or larger 2) preforms by injection molding, a cooling section that subjects the N preforms transferred from the injection molding section to forced cooling, a heating section that continuously transfers and heats the N cooled preforms, and a blow molding section that subjects the N heated preforms to stretch blow molding in n (n is an integer equal to or larger than 2) operations, the blow molding section simultaneously stretch blow molding M (M=N/n, M is a natural number) preforms among the N preforms into M containers.

CROSS REFERENCE TO RELATED APPLICATION(S)

This application is a continuation of U.S. patent application Ser. No.14/311,855, filed on Jun. 23, 2014, which is a continuation of U.S.patent application Ser. No. 13/867,513, filed on Apr. 22, 2013, andwhich is a continuation of International Patent Application No.PCT/JP2011/074273, having an international filing date of Oct. 21, 2011,which designated the United States and which claims priority fromJapanese Patent Application No. 2010-238199 filed on Oct. 25, 2010, theentirety of all of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an injection stretch blow moldingdevice and a molded article heating device.

2. Description of the Related Art

A blow molding system may utilize a 2-stage (cold parison) method or a1-stage (hot parison) method.

According to the 2-stage (cold parison) method, a blow molding system isprovided separately from a perform injection molding system, and theperform injection molding operation and the blow molding operation areimplemented off-line. A perform (parison) that has been produced byinjection molding using the injection molding system, and allowed tocool to room temperature (i.e., natural cooling) is supplied to the blowmolding system. The perform supplied from the injection molding systemis heated to the optimum blow temperature using a heating section, andsubjected to blow molding using a blow molding section to obtain acontainer. The preforms are intermittently or continuously transferredin the heating section, and at least one perform is intermittentlytransferred from the heating section to the blow molding section. Theblow molding section subjects at least one perform to blow molding toobtain at least one container (see U.S. Pat. No. 7,727,454, JapanesePatent Application Publication No. JP-A-2000-117821 and Japanese PatentApplication Publication No. JP-A-2007-276327).

According to the 2-stage (cold parison) method, the blow molding cycleof the blow molding system is set independently of the injection moldingcycle of the perform injection molding system, and throughput can beimproved. However, the energy efficiency decreases when using the2-stage (cold parison) method since the perform that has been cooled toroom temperature is heated to the optimum blow temperature.

An injection stretch blow molding system that utilizes the 1-stage (hotparison) method is configured so that the perform injection moldingoperation and the blow molding operation are implemented in-line.Specifically, N preforms that have been produced by injection moldingusing an injection molding section are subjected to blow molding in astate in which the preforms retain heat applied during injection moldingto obtain N containers. A typical blow molding system is configured sothat an injection molding section, a temperature control section, a blowmolding section, and an ejection section are provided at four positionson a turntable, and a perform or a container is rotated using a neckmold (see Japanese Patent Application Publication No. JP-A-53-22096). Inthis case, a perform that has been produced by injection molding in anupright state is transferred in the upright state, and subjected to blowmolding.

According to the 1-stage (hot parison) method, since the perform thatretains heat applied during injection molding is subjected to blowmolding to obtain a container, the thermal energy that is required forheating the perform to room temperature to the optimum blow temperatureis unnecessary. However, the blow molding cycle of the blow moldingsystem is the same as the injection molding cycle of the performinjection molding system, and the number of preforms simultaneouslyproduced by injection molding is the same as the number of preformssimultaneously subjected to blow molding.

The applicant of the present application developed a practical 1.5-stageinjection stretch blow molding system that effectively utilizes theadvantages of the 1-stage method and the 2-stage method (see JapanesePatent No. 2954858). The 1.5-stage injection stretch blow molding systemis basically configured so that the perform that retains heat appliedduring injection molding is subjected to blow molding to obtain acontainer in the same manner as in the case of using the 1-stage method.However, the blow molding cycle of the injection stretch blow moldingsystem can be reduced as compared with the injection molding cycle ofthe perform injection molding system, and the ratio of the number (N) ofpreforms simultaneously produced by injection molding to the number (M)of preforms simultaneously subjected to blow molding can be set to 3:1,for example.

SUMMARY OF THE INVENTION

Several aspects of the invention may provide a 1.5-stage injectionstretch blow molding device that effectively utilizes the advantages ofthe 1-stage method and the 2-stage method, and reduces the difference inmolding temperature between n blow molding operations to improve moldingquality when subjecting N (N is an integer equal to or larger than 2)preforms simultaneously produced by injection molding to blow molding inn operations in which M (M=N/n) preforms among the N preforms areseparately subjected to blow molding.

Several aspects of the invention may provide a 1.5-stage injectionstretch blow molding device that reduces the difference in temperaturebetween M preforms to improve molding quality when simultaneouslysubjecting M preforms to blow molding using a blow molding section.

Several aspects of the invention may provide a versatile 1.5-stageinjection stretch blow molding device that is configured so that theratio of the number (N) of preforms simultaneously produced by injectionmolding to the number (M) of preforms simultaneously subjected to blowmolding can be easily changed.

Several aspects of the invention may provide a molded article heatingdevice that does not utilize an endless chain, and can make use ofcontinuous transfer and intermittent transfer in combination.

According to a first aspect of the invention, there is provided aninjection stretch blow molding device including:

-   -   an injection molding section that produces N (N is an integer        equal to or larger than 2) preforms by injection molding;    -   a cooling section that subjects the N preforms produced by        injection molding to forced cooling;    -   a heating section that continuously transfers and heats the N        preforms subjected to forced cooling; and    -   a blow molding section that subjects the N preforms heated by        the heating section to stretch blow molding in n (n is an        integer equal to or larger than 2) operations, the blow molding        section simultaneously stretch blow molding M (M=N/n, M is a        natural number) preforms among the N preforms into M containers.

According to the first aspect of the invention, the difference inmolding temperature in each operation that subjects N preformssimultaneously produced by injection molding to blow molding in noperations in units of M preforms, or the difference in temperaturebetween the preforms, can be reduced when using the 1.5-stage method.This ensures that the resulting containers have uniform molding quality.When N preforms simultaneously produced by injection molding areseparately subjected to blow molding in n operations, the temperature ofM preforms that are initially subjected to blow molding tends to behigher than the temperature of M preforms that are subsequently(finally) subjected to blow molding. This is because the time from thecompletion of injection molding to the start of blow molding isinevitably shorter for the initial heating operation than for thesubsequent heating operation. Specifically, the advantage of the 1-stagemethod in that the injection molding operation and the blow moldingoperation are implemented in-line, and the perform is subjected to blowmolding in a state in which the perform retains heat applied duringinjection molding to obtain a container, results in an deterioration inmolding quality when using the 1.5-stage method in which the preformsare subjected to blow molding in n operations.

According to the first aspect of the invention, the ill effect of heatthat is applied during injection molding and retained by the preforms onthe perform temperature during the n blow molding operations can bereduced by subjecting the N preforms transferred from the injectionmolding section to forced cooling using a refrigerant. The temperaturedecrease gradient becomes steeper as the perform temperature increases.Therefore, when subjecting the preforms to forced cooling, thedifference in temperature between the N preforms before heatingdecreases as compared with the case where the preforms are not subjectedto forced cooling (i.e., subjected to natural cooling). Therefore, evenif the temperature of the perform varies depending on each injectioncavity of the injection molding section, the variation in temperaturedepending on each injection cavity can be reduced by subjecting thepreforms to forced cooling. Since it is not necessary to cool thepreforms to room temperature by forced cooling (differing from the2-stage method), heat that is applied during injection molding andretained by the preforms can be used for blow molding.

According to a second aspect of the invention, there is provided aninjection stretch blow molding device including:

-   -   an injection molding section that produces N (N is an integer        equal to or larger 2) preforms by injection molding;    -   a heating section that continuously transfers and heats the N        preforms transferred from the injection molding section; and    -   a blow molding section that subjects the N preforms heated by        the heating section to stretch blow molding in n (n is an        integer equal to or larger than 2) operations, the blow molding        section simultaneously stretch blow molding M (M=N/n, M is a        natural number) preforms among the N preforms into M containers.

When the N preforms are heated during intermittent transfer, the Npreforms are affected by the temperature distribution inside the heatingsection. Specifically, since the preforms that stop inside the heatingsection are heated during intermittent transfer, the temperature of thepreforms that stop at the inlet and the outlet of the heating sectiontends to decrease. When the output of some heaters included in theheating section is low, for example, the preforms are easily affected bysuch a situation during intermittent transfer. In contrast, when thepreforms are continuously transferred as in the first aspect and thesecond aspect of the invention, the preforms are uniformly heated, andhave an identical heat history. Therefore, the above adverse effect canbe prevented. This makes it possible to reduce the difference intemperature between the M preforms that are simultaneously stretch blowmolding.

In the injection stretch blow molding device according to the firstaspect or the second aspect of the invention, the heating section mayheat M preforms among the N preforms that are initially subjected toblow molding and M preforms among the N preforms that are subsequentlysubjected to blow molding in a row during continuous transfer.

When M preforms among the N preforms that are initially subjected tostretch blow molding and M preforms among the N preforms that aresubsequently subjected to blow molding are intermittently transferred ina row, the M preforms that are subjected to blow molding after the Mpreforms that are initially subjected to blow molding are nottransferred to the heating section (standby period) when the M preformsthat are initially subjected to blow molding are stopped in the heatingsection, and the difference in timing at which the preforms aretransferred to the heating section increases. Specifically, the heatingstart timing after injection molding thus differs in units of Mpreforms. The difference in temperature between M preforms that areinitially transferred to the heating section and M preforms that aresubsequently transferred to the heating section can be reduced bysubjecting the preforms to forced cooling before heating. The differencein timing of transfer to the heating section decreases when continuouslytransferring the preforms. A decrease in temperature of the performincreases as the standby time increases. However, the difference intemperature between M preforms that are initially transferred to theheating section and M preforms that are subsequently transferred to theheating section can be reduced by continuously transferring thepreforms. This makes it possible to reduce the difference in moldingtemperature in each operation when subjecting N preforms simultaneouslyproduced by injection molding to blow molding in n operations in unitsof M preforms.

In the injection stretch blow molding device according to the firstaspect of the invention, each of the N preforms may include a neck, theinjection molding section may produce the N preforms by injectionmolding in an upright state in which the neck is positioned on an upperside, the heating section may heat the N preforms in an inverted statein which the neck is positioned on a lower side, and the cooling sectionmay include an inversion section; N first cooling pots that are providedon a first side of the inversion section, and N second cooling pots thatare provided on a second side of the inversion section that is oppositeto the first side.

According to the above configuration, since the preforms can be heatedwhile transferring the preforms in the inverted state, it is possible tosimplify the structure of the transfer member that transfers the performin the heating section in the inverted state. Moreover, the coolingsection can subject the N preforms to forced cooling even during theinversion operation.

In the injection stretch blow molding device according to the firstaspect of the invention, a recess may be formed in an outer wall of eachof the N first cooling pots and the N second cooling pots, and theinversion section may include a flow passage for a refrigerant, the flowpassage including a first flow passage that communicates with the recessof the N first cooling pots to circulate the refrigerant, and a secondflow passage that communicates with the recess of the N second coolingpots to circulate the refrigerant.

The cooling efficiency can be improved by bringing the refrigerant intodirect contact with the outer wall of the first and second cooling pots.The first and second cooling pots are selectively used depending on thesize of the perform. The inversion section in which the flow passagesare formed can be used in common by merely forming the recess in theouter wall of the first and second cooling pots.

In the injection stretch blow molding device according to the firstaspect of the invention, M may be an even number, and M/2 small diameterholes and M/2 large diameter holes may be formed as cooling potinsertion holes in each of the first side and the second side of theinversion section, the M/2 small diameter holes and M/2 large diameterholes being alternately formed at an equal pitch in each of n rows.

When producing a perform having a large diameter, the number of preformssimultaneously produced by injection molding in the injection moldingsection is reduced to N/2. In this case, N/2 cooling pots can bedisposed on the first side and the second side by disposing the coolingpot in M/2 large diameter holes (n rows) formed in the inversionsection. Since it is possible to simultaneously produce N preformshaving a small diameter, N cooling pots can be disposed on the firstside and the second side using M/2 small diameter holes and M/2 largediameter holes. When a cooling pot having an identical size is used fora perform having a small diameter, a space formed when inserting thecooling pot into the large diameter hole may be filled with a liningmaterial or the like.

In the injection stretch blow molding device according to the firstaspect of the invention, the cooling section may subject the N preformsto forced cooling over a time equal to or longer than an injectionmolding cycle time required for the injection molding section to producethe N preforms by injection molding.

It is possible to further reduce the difference in perform temperaturein each of the n blow molding operation by thus providing a cooling timeequal to or longer than the injection molding cycle time.

In the injection stretch blow molding device according to the firstaspect of the invention, the N preforms in the upright state that havebeen produced by injection molding in an (m+1)th cycle may be held bythe N second cooling pots, and cooled while the N preforms in theupright state that have been produced by injection molding in an mthcycle are held by the N first cooling pots, and cooled in the invertedstate after being inverted by the inversion section.

According to the above configuration, the N preforms that have beenproduced by injection molding in the mth cycle are cooled in the N firstcooling pots until the N preforms that have been produced by injectionmolding in the (m+1)th cycle are held by the N second cooling pots. Thismakes it possible to provide a cooling time equal to or longer than theinjection molding cycle time.

In the injection stretch blow molding device according to the firstaspect of the invention, the heating section may be disposed along acontinuous transfer path that forms part of a transfer path in which(k×N) (k is an integer equal to or larger than 2) preforms thatcorrespond to k injection molding cycles are transferred.

In the injection stretch blow molding device according to the firstaspect of the invention, the transfer path may include a plurality ofsprockets, a plurality of transfer members that respectively hold oneperform, two transfer members among the plurality of transfer membersthat are adjacent to each other in a transfer direction coming incontact with each other, and a guide rail that guides the plurality oftransfer members along the transfer direction to engage the plurality ofsprockets.

According to a third aspect of the invention, there is provided a moldedarticle heating device including:

-   -   a transfer path that transfers a plurality of molded articles;        and    -   a heating section that is provided along the transfer path,    -   the transfer path including a plurality of sprockets, a        plurality of transfer members that respectively hold one molded        article, two transfer members among the plurality of transfer        members that are adjacent to each other in a transfer direction        coming in contact with each other, and a guide rail that guides        the plurality of transfer members along the transfer direction        to engage the plurality of sprockets.

According to the first aspect and the third aspect of the invention, aplurality of transfer members can be continuously transferred at aconstant pitch without using an endless chain. For example, a pluralityof transfer members can be transferred by causing the upstream-sidetransfer member that engages the continuous drive sprocket to press thetransfer member that does not engage the sprocket on the downstreamside. Since an endless chain is not used, the downstream-side transfermember that has been continuously transferred can be intermittentlytransferred by causing the transfer member to engage the intermittentdrive sprocket. Therefore, continuous transfer and intermittent transfercan be performed using an identical transfer path. It is also possibleto deal with a change in the number M of preforms simultaneouslysubjected to blow molding by utilizing each transfer member. A structurethat does not utilize an endless chain may be widely used for a heatingdevice for a molding device or a heating device for a crystallizationdevice in addition to the 1.5-stage injection stretch blow moldingdevice.

In the injection stretch blow molding system according to the firstaspect of the invention or the molded article heating device accordingto the third aspect of the invention, M transfer members that areadjacent to each other in the transfer direction may be connected by aconnection member to form one transfer jig, some sprockets among theplurality of sprockets that are adjacent to each other in the transferdirection may be continuously driven, and other sprockets among theplurality of sprockets that are adjacent to each other in the transferdirection may be intermittently driven at a high speed as compared withthe some sprockets.

This makes it possible to easily implement continuous transfer andintermittent transfer in units of M preforms or a plurality of moldedarticles. For example, the upstream-side transfer member can be causedto come in contact with the downstream-side transfer member that iscontinuously transferred, by driving the intermittent drive sprocket(discharge device) that engages the upstream-side transfer member at ahigh speed as compared with the downstream-side continuous drivesprocket. It is also possible to intermittently transfer the transferjig that has been continuously transferred by intermittentlytransferring some of the M downstream-side transfer members at a highspeed. When implementing a heating device for a device other than the1.5-stage injection stretch blow molding device, a plurality of transfermembers that are adjacent to each other in the transfer direction may beconnected by the connection member to form one transfer jig.

In the injection stretch blow molding device according to the firstaspect of the invention, the cooling section may transfer the N preformssubjected to forced cooling to n transfer jigs.

According to the above configuration, the difference in temperature canbe reduced by subjecting the N preforms simultaneously produced byinjection molding to forced cooling, and the M preforms can be mountedon n transfer members, and heated during continuous transfer.

The injection stretch blow molding device according to the first aspectof the invention may further include a discharge device thatsequentially discharges the n transfer jigs, and causes a forefronttransfer member of the transfer jig to engage a drive sprocket among theplurality of sprockets that is positioned on a most upstream side.

This makes it possible to sequentially transfer n transfer jigs, andsupply the transfer jigs to the continuous transfer path in a row.

The injection stretch blow molding device according to the first aspectof the invention may further include an intermittent transfer mechanismthat intermittently transfers the M preforms heated by the heatingsection to the blow molding section.

According to the above configuration, the preforms can be continuouslytransferred in the heating section that may affect the molding quality,and M preforms (blow molding unit) can then be intermittentlytransferred.

The injection stretch blow molding device according to the first aspectof the invention may further include a removal device that removes the Npreforms from the injection molding section; a transfer device thattransfers the N preforms from the removal device to the cooling section,the injection molding section may simultaneously produce M preformsamong the N preforms by injection molding in each of n rows that areparallel to a first direction, a first interval between two adjacentpreforms in each of the n rows at a center position in the firstdirection may differ from a second interval between two other preformswhen M is an even number, the removal device may transfer the M preformsin each of the n rows from the injection molding section along a seconddirection that is perpendicular to the first direction, and change aperform arrangement pitch in the second direction to a narrow pitch, thetransfer device may change the first interval so that the first intervalcoincides with the second interval, and the cooling section maysimultaneously subject M preforms among the N preforms to forced coolingin each of n rows that are parallel to the first direction.

According to the above configuration, since forced cooling in thecooling section and continuous heating in the heating section can beimplemented at a pitch narrower than the injection molding pitch, thesize of the device can be reduced. The first interval between twoadjacent preforms in each of the n rows at the center position in thefirst direction is set to differ from the second interval between twoother preforms during injection molding taking account of thearrangement of the nozzle of a hot runner mold. In this case, since thetransfer device can set the first interval and the second interval toconstant values, the preforms can be arranged at equal intervals in eachof the n rows. Therefore, the interval between the preforms that arecontinuously transferred in the heating section can be made constant,and the effects from the adjacent preforms during continuous transfercan be made uniform.

According to a fourth aspect of the invention, there is provided aninjection stretch blow molding device including:

-   -   an injection molding section that produces N (N is an integer        equal to or larger 2) preforms by injection molding, the        injection molding section simultaneously producing M (M=N/n, M        is a natural number) preforms by injection molding in each of n        (n is an integer equal to or larger than 2) rows that are        parallel to a first direction;    -   a cooling section that subjects the N preforms transferred from        the injection molding section in a second direction        perpendicular to the first direction to forced cooling in each        of n rows that are parallel to the first direction in units of M        preforms;    -   a heating section that continuously transfers and heats the N        preforms that have been cooled and transferred in the first        direction in units of M preforms along a roundabout path; and    -   a blow molding section that subjects the N preforms heated by        the heating section to stretch blow molding in n (n is an        integer equal to or larger than 2) operations, M preforms being        simultaneously and intermittently transferred to the blow        molding section along the second direction, and the blow molding        section simultaneously stretch blow molding M preforms into M        containers.

The injection stretch blow molding device according to the fourth aspectof the invention operates in the same manner as the injection stretchblow molding device according to the first aspect of the invention, andis also characterized in that the injection molding section, the coolingsection, and the blow molding section are arranged along the seconddirection, and the heating section is disposed along a roundabout pathin at least an area adjacent to the cooling section in the firstdirection. This makes it possible to reduce the total length of thedevice in the second direction. Since the heating section heats thepreforms that retain heat applied during injection molding, and theheating transfer path can be formed along a roundabout path, an increasein the total width of the device in the first direction can besuppressed. Therefore, the installation area of the device can bereduced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view illustrating an injection stretch blow moldingdevice according to one embodiment of the invention.

FIG. 2 is a front view illustrating the injection stretch blow moldingdevice illustrated in FIG. 1.

FIGS. 3A and 3B are views illustrating a perform holding state and aperform holding cancellation state of a perform transfer device disposedbetween an injection molding section and a cooling section.

FIG. 4 is a front view illustrating a cooling section that includes aninversion section.

FIG. 5 is a front view illustrating a transfer member that transfers aperform in a heating section.

FIG. 6 is a view illustrating a state in which a neck of a perform isshielded from heat using the transfer member illustrated in FIG. 5.

FIG. 7 is a front view illustrating a transfer jig formed by connectingM transfer members using a connection member.

FIGS. 8A and 8B are respectively a front view and a plan viewillustrating a parallel transfer device that transfers a plurality oftransfer jigs in parallel.

FIG. 9 is a view illustrating intermittent transfer and continuoustransfer in an injection stretch blow molding device.

FIG. 10 is a characteristic diagram illustrating a change in performtemperature in one embodiment of the invention and a comparativeexample.

FIG. 11 is a characteristic diagram illustrating a change in performtemperature in one embodiment of the invention and Comparative Examples1 and 2.

FIG. 12 is a plan view illustrating a modification of a removal device.

FIGS. 13A and 13B are side views illustrating the fixed pot supportstage and the movable pot support stage illustrated in FIG. 12.

FIGS. 14A and 14B are views illustrating a wide pitch state and a narrowpitch state of the fixed pot support stage and the movable pot supportstage illustrated in FIG. 12.

FIGS. 15A and 15B are rear views illustrating a wide gap state and anarrow gap state of a stationary plate and a movable plate in a performtransfer device.

FIGS. 16A and 16B are side views illustrating the perform transferdevice illustrated in FIGS. 15A and 15B, and FIG. 16B is across-sectional view illustrating a perform holder.

FIG. 17 is a cross-sectional view illustrating a modification of thecooling section illustrated in FIG. 4.

FIGS. 18A to 18C are views illustrating cooling pots that receive aperform having a different size.

FIG. 19 is a cross-sectional view illustrating the cooling sectionillustrated in FIG. 17, and illustrates a state in which a cooling pothas been removed.

FIGS. 20A and 20B are plan views illustrating a stationary plate onwhich a cooling pot having a different size is secured.

FIG. 21 is a schematic oblique view illustrating an inversion transfermechanism.

FIG. 22 is a front view illustrating an inversion transfer mechanism.

FIG. 23 is a plan view illustrating an inversion transfer mechanism.

FIG. 24 is a view illustrating a specific example of a blow moldingsection and an intermittent transfer mechanism.

FIG. 25 is a view illustrating a blow molding section.

FIG. 26 is a perspective view illustrating transfer from an inversiontransfer mechanism to an intermittent transfer mechanism.

FIG. 27 is a front view illustrating transfer from an inversion transfermechanism to an intermittent transfer mechanism.

DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

Exemplary embodiments of the invention are described in detail belowwith reference to a comparative example. Note that the followingexemplary embodiments do not in any way limit the scope of the inventiondefined by the claims laid out herein. Note also that all of theelements described in connection with the following exemplaryembodiments should not necessarily be taken as essential elements of theinvention.

1. Injection Stretch Blow Molding Device

FIG. 1 is a plan view illustrating an injection stretch blow moldingdevice, and FIG. 2 is a front view illustrating the injection stretchblow molding device. As illustrated in FIGS. 1 and 2, an injectionmolding section 10, a cooling section 20, a heating section 30, and ablow molding section 40 are provided on a stage 1 of the injectionstretch blow molding device.

Several embodiments of the invention implement a 1.5-stage injectionstretch blow molding device that utilizes a 1-stage method in which theinjection molding operation and the blow molding operation areimplemented in-line, but has a configuration in which the number ofpreforms simultaneously produced by injection molding differs from thenumber of preforms simultaneously subjected to blow molding. Theinjection stretch blow molding device includes the cooling section 20between the injection molding section 10 and the heating section 30. Thecooling section 20 subjects the perform transferred from the injectionmolding section 10 to forced cooling. Specifically, the configuration ofthe injection stretch blow molding device clearly differs from aconfiguration in which the perform immediately after being produced bythe injection molding section 10 is subjected to forced cooling to therelease temperature using the injection core mold and/or the injectioncavity mold.

In several embodiments of the invention, the difference in moldingtemperature in each operation when subjecting N preforms simultaneouslyproduced by injection molding to blow molding in n operations in unitsof M preforms, is reduced by subjecting the preforms to forced coolingbefore heating so that the resulting containers have uniform moldingquality.

The planar layout of the 1.5-stage injection stretch blow molding deviceis described below. As illustrated in FIGS. 1 and 2, the injectionmolding section 10 produces N preforms by injection molding, theinjection molding section 10 simultaneously producing M (M=N/n, M is anatural number) preforms by injection molding in each of n (n is aninteger equal to or larger than 2) rows that are parallel to a firstdirection D1. The cooling section 20 subjects the N preforms transferredfrom the injection molding section 10 in a second direction D2perpendicular to the first direction D1 to forced cooling in each of nrows that are parallel to the first direction D1 in units of M preforms.The heating section 30 continuously transfers and heats the N preformsthat have been cooled and transferred in the first direction D1 in unitsof M preforms along a roundabout path. The blow molding section 40subjects the N preforms that have been heated to stretch blow molding,the blow molding section 40 simultaneously stretch blow molding Mpreforms among the N preforms into M containers, the M preforms beingintermittently transferred to the blow molding section 40 along thesecond direction D2.

The injection stretch blow molding device is configured so that theinjection molding section 10, the cooling section 20, and the blowmolding section 40 are arranged on the stage 1 along the seconddirection D2, and the heating section 30 is disposed in at least an areaadjacent to the cooling section 20 in the first direction D1. This makesit possible to reduce the total length of the injection stretch blowmolding device in the second direction D2. Since the heating section 30heats the preforms that retain heat applied during injection molding,and the heating transfer path can be formed along a roundabout path, anincrease in the total width of the injection stretch blow molding devicein the first direction D1 can be suppressed. Therefore, the installationarea of the injection stretch blow molding device can be reduced.

2. Injection Molding Section

The injection molding section 10 includes a clamping mechanism 102 thatclamps molds along four tie rods 100 illustrated in FIG. 1. The clampingmechanism 102 clamps an injection core mold 104 (see FIG. 2) and aninjection cavity mold 106. An injection device 110 brings a nozzle intocontact with a hot runner mold, and injects a resin to produce a performby injection molding.

As illustrated in FIG. 1, the number N of preforms simultaneouslyproduced by injection molding in the injection molding section 10 is 24(3 (rows)×8) at a maximum for example. When the diameter of the performis large, four preforms are produced by injection molding in each row(i.e., N=12). For example, twenty-four (N=24) injection cavity molds 106are disposed in the injection molding section 10 when molding a1.5-liter container, and twelve (N=12) injection cavity molds 106 aredisposed in the injection molding section 10 when molding a 5-litercontainer. The injection core mold 104 and the injection cavity mold 106have a function of subjecting the perform to forced cooling using arefrigerant, and the perform is cooled to a temperature at which theperform can be removed from the injection core mold 104 and theinjection cavity mold 106. The cooling section 20 cools the perform in amanner differing from the injection core mold 104 and the injectioncavity mold 106.

The injection molding section 10 includes a removal device 120 thatremoves the N preforms produced by injection molding. The removal device120 is configured so that N (3(rows)×8) pots 122 (i.e., holding members)can move horizontally between a receiving position under the injectioncore mold 104 and a transfer position that is situated outside the spacedefined by the tie rods 100. The row pitch of the pots 122 is changedfrom a wide pitch (injection molding pitch) at the receiving position toa narrow pitch at the transfer position during the horizontal movementof the pots 122. Note that two pots among the three pots drawn at thetransfer position are pots used for a perform having a large diameterand a large length (i.e., the pots drawn at the receiving position), andthe remaining pot among the three pots is a pot used for a performhaving a small diameter and a small length. Specifically, the size andthe number of pots 122 are changed corresponding to the size of theperform. In FIG. 2, the pots 122 are drawn by the solid line at thereceiving position and the transfer position for convenience ofillustration. The pots 122 stand still at the receiving position or thetransfer position in the actual situation.

The injection molding section 10 that includes the removal device 120may be implemented in the same manner as that included in the performmolding device disclosed in Japanese Patent Application No. 4148576, forexample. Note that the injection molding section 10 is not limitedthereto.

3. Cooling Section

The N preforms produced by injection molding are transferred to thecooling section 20 that subjects the preforms to forced cooling. Asillustrated in FIG. 2, a perform transfer device 50 is provided in orderto transfer the preforms. The perform transfer device 50 transfers the Npreforms held by the pots 122 (3 rows) that are situated at the transferposition (see FIG. 2) to the cooling section 20. The perform transferdevice 50 includes a perform holder 500 (see FIGS. 3A and 3B), a firstair cylinder 510 that moves the perform holder 500 upward and downwardin the direction A illustrated in FIG. 2, and a second air cylinder 520that horizontally moves the perform holder 500 and the first aircylinder 510 in the direction B illustrated in FIG. 2 (see FIG. 2).

As illustrated in FIG. 3A, the perform holder 500 includes a hollowholder main body 502 that comes in contact with the end face of a neck2A of a perform 2 held by the pot 122 (see FIG. 2), a core 504, and arod 506, the core 504 and the rod 506 being movably supported by theholder main body 502. The core 504 can be inserted into the neck 2A ofthe perform 2 by lowering the rod 506 using a drive mechanism (notillustrated in the drawings). The perform 2 is sucked via a suction holeformed in the core 504 and the rod 506, and adheres to the holder mainbody 502. The perform 2 is released by removing the core 504 from theneck 2A, and stopping the suction operation (see FIG. 3B).

As illustrated in FIG. 1, the arrangement pitch of the preforms(injection molding cavities) (3 rows) may be increased in the injectionmolding section 10 at the center in each row in order to provide auniform resin path length in the hot runner mold. In this case, theperform transfer device 50 may have a function of adjusting thearrangement pitch of the preforms in each row to a uniform pitch.

As illustrated in FIG. 4, the cooling section 20 may include aninversion section 200, N first cooling pots 210 that are provided on afirst side 201 of the inversion section 200, and N second cooling pots220 that are provided on a second side 202 of the inversion section 200opposite to the first side 201. The first cooling pots 210 and thesecond cooling pots 220 are cooled by a refrigerant that is circulatedthrough a refrigerant passage 230. The first cooling pots 210 and thesecond cooling pots 220 have a suction hole 240 for sucking the perform2. The inversion section 200 can be inverted around a shaft 204. Theinversion section 200 can be moved upward and downward using a ballscrew that is driven by a servomotor 206 (i.e., drive source) (see FIG.2).

The injection molding section 10 produces the N preforms 2 by injectionmolding in an upright state in which the neck 2A is positioned on theupper side. The inversion section 200 can invert the N preforms 2 in theupright state to an inverted state in which the neck 2A is positioned onthe lower side. Specifically, the inversion operation can be performedduring cooling, and a long cooling time can be provided withoutseparately providing an inversion time and the like.

The cooling section 20 can subject the N preforms 2 to forced coolingover a time equal to or longer than the injection molding cycle timerequired for the injection molding section 10 to produce the N preforms2 by injection molding.

Therefore, N preforms 2 in the upright state that have been produced byinjection molding in the (m+1)th cycle are held by the N second coolingpots 220, and cooled while N preforms 2 in the upright state that havebeen produced by injection molding in the mth cycle are held by the Nfirst cooling pots 210, inverted by the inversion section 200, andcooled in the inverted state. Specifically, N preforms 2 that have beenproduced by injection molding in the mth cycle and N preforms 2 thathave been produced by injection molding in the (m+1)th cycle aretemporarily present in the inversion section 200. Therefore, the Npreforms 2 that have been produced by injection molding in the mth cycleare subjected to forced cooling over a time equal to or longer than theinjection molding cycle time of the N preforms 2 that are produced byinjection molding in the (m+1)th cycle.

The perform subjected to forced cooling by the cooling section 20 over atime equal to or longer than the injection molding cycle time is notcooled to room temperature. However, a perform formed of polyethyleneterephthalate (PET) can be cooled to a temperature of about 70 to 80° C.that is lower than the release temperature by about 10° C.

The forced cooling step performed by the cooling section 20 reduces thedifference in temperature between the N preforms 2 that have beensimultaneously produced by injection molding immediately before heatingeven when the heating start timing is changed. When subjecting the Npreforms 2 that retain heat applied during injection molding to naturalcooling, a significant difference in temperature is observed between theN preforms 2 immediately before heating depending on the natural coolingtime.

The 1.5-stage injection stretch blow molding device according to oneembodiment of the invention subjects the preforms 2 transferred from theinjection molding section 10 to forced cooling as described above. Sincethe preforms 2 need not be cooled to room temperature, and retain heatapplied during injection molding, high energy efficiency achieved by a1-stage device can also be achieved.

4. Heating Section

The heating section 30 heats the cooled N preforms 2 to an optimumstretch temperature. The heating section 30 heats the N preforms 2 in aninverted state in which the neck 2A is positioned on the lower side. Theheating section 30 heats the N preforms 2 while continuouslytransferring the N preforms 2.

The heating section 30 is disposed along a continuous transfer path 310that forms part of a transfer path 300 that forms a closed loop or acirculation loop in which (k×N) preforms 2 (k is an integer equal to orlarger than 2) that correspond to k cycles are transferred. The transferpath 300 may include a plurality of sprockets 321 to 328 (see FIG. 1), aplurality of transfer members 330 (see FIGS. 5 and 6) that can engagethe plurality of sprockets 321 to 328, and respectively hold one perform2, and a guide rail 340 (see FIGS. 5 and 6) that guides the plurality oftransfer members 330 along the transfer direction. The transfer path 300includes the upstream-side continuous transfer path 300 and adownstream-side intermittent transfer path 312.

As illustrated in FIGS. 5 and 6, the transfer member 330 is configuredso that a holding section 332 that is inserted into the neck 2A issecured on one end (upper end) of a rotation shaft 331, and a sprocket333 to which a rotation drive force is applied is secured on the otherend (lower end) of the rotation shaft 331. The sprocket 333 engages astationary or movable chain 350 disposed in the heating section 30 (seeFIG. 1), and rotates together with the rotation shaft 331.

The heating section 30 may have a configuration in which quartz heaters30A (i.e., heaters) and a mirror (not illustrated in the drawings) aredisposed on either side of the continuous transfer path 310, the quartzheaters 30A being disposed in a plurality of stages in the heightdirection, and disposed at intervals in the transfer direction. In theheating section 30, a hot blast may be blown from the back side of theheater, and guided along the transfer direction of the preforms 2. Notethat a variation in temperature does not occur since the preforms 2 arerotated during heating.

A heat shield member 360 is supported by a slider 361 disposed aroundthe rotation shaft 331. When the slider 361 is moved upward by a cam 362(see FIG. 6), the heat shield member 360 surrounds the neck 2A of theperform 2 to shield the neck 2A from heat.

As illustrated in FIG. 7, ring-like members 334 of two transfer members330 adjacent to each other in the transfer direction come in contactwith each other. The ring-like member 334 is supported by the rotationshaft 331 via a rotation bearing 335. The ring-like member 334 has acircular outer circumferential shape, for example. The adjacentring-like members 334 come in rolling contact with each other.Therefore, the adjacent ring-like members 334 can maintain the rollingcontact relationship even when transferred along a curved transfer path.

As illustrated in FIG. 7, M (e.g., M=8) transfer members 330 that areconsecutive in the transfer direction may be connected by a connectionmember 371 to form a transfer jig 370. The connection member 371includes an inner link 372 that connects one rotation shaft 331 withanother rotation shaft 331 adjacent thereto on the upstream side, and anouter link 373 that connects one rotation shaft 331 with anotherrotation shaft 331 adjacent thereto on the downstream side, for example.The connection member 371 that is formed by connecting the inner link372 and the outer link 373 forms a chain, and the chain (connectionmember) 371 engages the plurality of sprockets 321 to 328 illustrated inFIG. 1. Specifically, the connection member 371 that connects the Mtransfer members 330 is used as a chain instead of using an endlesschain.

When forming the transfer jig 370 by connecting the M transfer members330 (see FIG. 7), it is necessary to provide the transfer jig 370corresponding to the number M of preforms simultaneously subjected toblow molding that may be changed. On the other hand, it is easy to dealwith a change in the number M of preforms simultaneously subjected toblow molding when using the transfer members 330 that are not connected.However, when using the transfer members 330 that are not connected, itis necessary to provide each transfer member 330 with a member thatcorresponds to the chain that engages the continuous/intermittent drivemembers (e.g., sprockets 231 to 238).

The sprockets 321, 323, and 324 among the plurality of sprockets 321 to328 disposed in the transfer path 300 may be continuous drive sprockets,the sprockets 325 and 327 among the plurality of sprockets 321 to 328may be intermittent drive sprockets, and the sprockets 322, 326, and 328among the plurality of sprockets 321 to 328 may be driven sprockets, forexample. A continuous drive source drives the sprocket 324, and thedriving force is transmitted to the continuous drive sprockets 321 and323 via belts 328A and 328B, for example. An intermittent drive sourcedrives the sprocket 325, and the driving force is transmitted to theintermittent drive sprocket 327 via a belt 329, for example.Specifically, an upstream path 320 of the transfer path 300 is acontinuous drive path, and the downstream path 312 is an intermittentdrive path (i.e., the loop-like transfer path 300 includes a continuousdrive path and an intermittent drive path in combination).

A parallel driving device 380 that drives (n+1) or more (e.g., four)transfer jigs 370 in parallel is disposed under the cooling section 20illustrated in FIG. 2. As illustrated in FIGS. 8A and 8B, the paralleldriving device 380 is formed by attaching the ends of a plurality oftransfer rails 384 to two chains 383 that are fitted around sprockets381 and 382 that are disposed on each end of each shaft. The transferjig 370 that is guided by the driven sprocket 328 illustrated in FIG. 1is slid into each transfer rail 384 in the longitudinal direction, andthe eight ring-like members 334 of the transfer jig 370 are placed onand supported by the transfer rail 384.

One of the sprockets 381 and 382 is then rotated by one step to transferthe transfer rail 384 by one step. The above operation is repeated todispose four transfer jigs 370 on the parallel driving device 380. Asillustrated in FIG. 2, the preforms 2 are transferred from the coolingsection 20 (inversion section 200) to n (n=N/M (e.g., n=3))downstream-side transfer jigs 370.

As illustrated in FIG. 1, the transfer jig 370 in the first row amongthe transfer jigs 370 (four rows) disposed on the parallel drivingdevice 380 is pushed out in the arrow direction C by a discharge device(not illustrated in FIG. 1) formed by an air cylinder or the like.Therefore, the eight transfer members 330 (transfer jig 370) that holdthe perform 2 sequentially engage the continuous drive sprocket 321, andare sequentially (continuously) transferred.

In FIGS. 1 and 8B, the position of the forefront transfer member 330(perform 2) of one transfer jig 370 is marked for convenience ofexplanation. The forefront transfer member 330 of the transfer jig 370in the first row in FIG. 8B is transferred by the discharge device, andengages the continuous drive sprocket 321 on the most upstream side. Acontinuous transfer force is then applied to the transfer jig 370 fromthe continuous drive sprocket 321.

When the driving force is applied to each transfer jig 370 (transfermember 330) that engages the continuous drive sprockets 321, 323, and324 present in the continuous transfer path 310, another transfer jig370 (transfer member 330) that is positioned on the upstream side anddoes not engage the continuous drive sprocket is pressed, and aplurality of transfer jigs 370 are continuously transferred along thecontinuous transfer path 310.

A schematic transfer motion of the preforms 2 in the injection moldingstep, the cooling step, and the heating step is described below withreference to FIG. 9. In FIG. 9, reference signs I1 to I8 indicateintermittent transfer, and reference signs C1 to C3 indicate continuoustransfer.

The N preforms 2 that have been produced by injection molding in theinjection molding section 10 are removed from the pots 122 after thepots 122 have been intermittently transferred by the removal device 120in the direction indicated by I1. The preforms 2 are transferred to thecooling section 20 via the perform transfer device 50, inverted in thecooling section 20 in the direction indicated by 12, and mounted onthree transfer jigs 370 disposed on the parallel driving device 380 inunits of M preforms.

The forefront transfer jig 370 disposed on the parallel driving device380 is intermittently transferred by the discharge device (notillustrated in FIG. 9) in the direction indicated by 13, and transferredto the continuous transfer path 310. A plurality of transfer jigs 370are continuously transferred along the continuous transfer path 310 dueto the driving force applied by the continuous drive sprockets 321, 323,and 324, and contact between the adjacent transfer members 370 via thering-like members 334. The preforms 2 are heated by the heating section30 while rotating.

In FIG. 1, the intermittent transfer path 312 on the downstream side ofthe transfer path 300 is in a state immediately after completion ofintermittent transfer. A blank area that corresponds to the length ofone transfer jig 370 is present on the upstream side of the transfer jig370 that engages the continuous drive sprocket 324. Specifically, aplurality of transfer jigs 370 positioned on the upstream side of thetransfer jig 370 that engages the continuous drive sprocket 324 areintermittently transferred at a speed higher than that during continuoustransfer due to intermittent drive of the intermittent drive sprockets325 and 327 (see the arrow indicated by 14 in FIG. 9).

The continuous drive sprocket 324 is continuously driven from the stateillustrated in FIG. 1, and the transfer jigs 370 that engage thecontinuous drive sprocket 324 are continuously transferred. In thiscase, the intermittent drive sprocket 325 engages the transfer jigs 370,and rotates dependently. The intermittent drive sprocket 325 then comesin contact with the upstream-side transfer jig 370 that hasintermittently stopped in the intermittent transfer path 312 via thering-like member 334, and intermittent transfer is performed at thistiming. Therefore, a blank area that corresponds to the length of onetransfer jig 370 is present again on the upstream side of the transferjig 370 that engages the continuous drive sprocket 324. The aboveoperation is repeated. The transfer jig 370 is sequentially transferredto the transfer rail 384 of the parallel driving device 380 (see FIG.8A) each time intermittent drive is performed (see the arrow indicatedby IS in FIG. 9). The transfer jigs 370 that hold M new preforms 2 areintermittently supplied to the continuous transfer path 310 insynchronization with the above operation (see the arrow indicated by 13in FIG. 9).

5. Blow Molding Section

The blow molding section 40 subjects M preforms to biaxial stretching byblowing air and vertically driving a stretching rod to obtaincontainers. A blow cavity mold, a blow core mold, and an optional bottommold (not illustrated in the drawings) are clamped. The structure ofeach mold is well-known in the art. Therefore, description thereof isomitted. An intermittent transfer mechanism 400 is provided to transferM preforms 2 from the heating section 30 to the blow molding section 40.The intermittent transfer mechanism 400 includes a pair of neck holdingplates 401 and 402, for example. In FIG. 1, the neck holding plates 401and 402 are illustrated at a position before or after the movement. Thepreforms 2 are transferred in a state in which the neck 2A is held bythe neck holding plates 401 and 402.

In one embodiment of the invention, the preforms 2 are subjected to blowmolding in the blow molding section 40 in the upright state, andtransferred by the neck holding plates 401 and 402 in the upright state.The neck holding plates 401 and 402 are also used when removing the Mcontainers obtained by blow molding using an ejection section 60.

M transfer arms (not illustrated in the drawings) are used to transfer Mpreforms 2 from the heating section 30 to the blow molding section 40.As illustrated in FIG. 2, M preforms 2 are removed in the inverted statefrom the transfer jigs 370 that have been intermittently transferred onthe downstream side of the transfer path 300 in the direction D, andinverted to the upright state in the direction F using the transfer arms(see the arrow indicated by 16 in FIG. 9).

The transfer arm also has a function of changing the arrangement pitchfrom the narrow pitch during heating to the wide pitch during blowmolding (see FIG. 2). A state in which eight (M=8) preforms having asmall diameter and a small length are inverted and changed in pitch, anda state in which four (M=4) preforms having a large diameter and a largelength are inverted and changed in pitch, are drawn in FIG. 2 forreference (see the arrows indicated by D and F).

The preforms 2 are then transferred from the transfer arms to the neckholding plates 401 and 402, and transferred to the blow molding section40 (see the arrow indicated by 17 in FIG. 9). Note that the operation(indicated by 17 in FIG. 9) that transfers the preforms 2 to the blowmolding section 40, and the operation (indicated by 17 in FIG. 9) thattransfers the containers obtained by blow molding to the ejectionsection 60, may be performed at the same time using the neck holdingplates 401 and 402.

6. Advantageous Effects of Injection Stretch Blow Molding Device

According to the embodiments of the invention, the difference in moldingtemperature in each operation when subjecting N preforms simultaneouslyproduced by injection molding to blow molding in n operations in unitsof M preforms, can be reduced when using the 1.5-stage method. Thedetails thereof are described below with reference to FIG. 10 using acomparative example.

FIG. 10 shows the perform temperature TE according to one embodiment ofthe invention, and the perform temperature TC in the 1.5-stage devicedisclosed in Japanese Patent No. 2954858 (comparative example). In oneembodiment of the invention, twenty-four (N=24) preforms weresimultaneously produced by injection molding, subjected to forcedcooling, heated, and then subjected to blow molding in units of eight(M=8) preforms. In the comparative example, eight preforms weresimultaneously produced by injection molding, heated during intermittenttransfer, and then subjected to blow molding in units of four preforms.

In FIG. 10, the time T1 is the forced cooling period using the coolingsection 20 according to one embodiment of the invention, the time T2 isthe intermittent transfer time using the heating section according tothe comparative example, and the time T3 is the continuous transfer timeusing the heating section 30 according to one embodiment of theinvention.

In the comparative example shown in FIG. 10, the temperature of fourpreforms that are initially subjected to blow molding increases byheating according to the characteristics TC1, and the temperature offour preforms that are subsequently subjected to blow molding increasesby heating according to the characteristics TC2. The characteristics TC1and the characteristics TC2 differ as to the temperature immediatelybefore heating. A relatively large temperature difference Δt is observedbetween the characteristics TC1 and the characteristics TC2. Thetemperature difference Δt also occurs during blow molding (see FIG. 10).

In one embodiment of the invention shown in FIG. 10, the temperature ofeight preforms that are initially subjected to blow molding increases byheating according to the characteristics TE1, the temperature of eightpreforms that are subsequently subjected to blow molding increases byheating according to the characteristics TE2, and the temperature ofeight preforms that are subsequently subjected to blow molding increasesby heating according to the characteristics TE3. The characteristicsTE1, the characteristics TE2, and the characteristics TE3 differ as tothe temperature immediately before heating. However, the temperaturedifference ΔT between the characteristics TE1, the characteristics TE2,and the characteristics TE3 is significantly smaller than thetemperature difference Δt in the comparative example. The smalltemperature difference ΔT also occurs during blow molding (see FIG. 10).

Specifically, when using the 1.5-stage method in which preformssimultaneously produced by injection molding are separately subjected toblow molding in n operations, the temperature of preforms that areinitially subjected to blow molding tends to be higher than thetemperature of preforms that are subsequently subjected to blow molding.This is because the time from the completion of injection molding to thestart of heating is inevitably shorter for the initial heating operationthan for the subsequent heating operation. The above tendencysignificantly occurs when the heating section heats preforms that areinitially subjected to blow molding and preforms that are subsequentlysubjected to blow molding among the preforms simultaneously produced byinjection molding while transferring the preforms in a row.Specifically, the heating start time after completion of injectionmolding differs in units of preforms that are simultaneously subjectedto blow molding.

FIG. 11 shows the heat history of the perform temperatures TC1 and TC2achieved by Japanese Patent No. 2954858 (1.5-stage method) (see FIG. 10)(Comparative Example 1), the perform temperatures TD1 to TD3 achieved bythe 2-stage method (e.g., U.S. Pat. No. 7,727,454) (Comparative Example2), and the perform temperatures TE1 to TE3 according to one embodimentof the invention (FIG. 11 shows detailed analysis results for theperform temperature shown in FIG. 10).

In FIG. 11, the perform temperature TC of Comparative Example 1 and theperform temperature TE according to one embodiment of the inventionchange in an identical manner before the forced cooling period T1according to one embodiment of the invention starts. As is clear fromFIG. 11, the temperature decreases rapidly during the forced coolingperiod T1 according to one embodiment of the invention. However, thetemperature decrease gradient θ2 during natural cooling after the forcedcooling period T1 has elapsed is smaller than the temperature decreasegradient θ1 of Comparative Example 1 in which only natural cooling iseffected without providing the forced cooling period. This is becausethe perform temperature TE according to one embodiment of the inventionis lower than the perform temperature TC of Comparative Example 1 due tothe forced cooling period T1, and the temperature decrease ratedecreases as the perform temperature decreases.

In Comparative Example 1, since the preforms are intermittentlytransferred in the heating section, the preforms that are subjected toblow molding after the preforms that are initially subjected to blowmolding are not transferred to the heating section (standby period) atleast when the preforms that are initially subjected to blow molding arestopped in the heating section, and the difference in timing at whichthe preforms are transferred to the heating section increases. Since theperform temperature TC decreases by the relatively large temperaturedecrease gradient θ1 during the standby period, the difference betweenthe temperature TC1 of the preforms that are initially transferred tothe heating section and the temperature TC2 of the preforms that aresubsequently transferred to the heating section increases.

According to one embodiment of the invention, the difference in timingat which the preforms are transferred to the heating section is smallsince continuous transfer is employed. The difference between thetemperatures TE1, TE2, and TE3 of the preforms sequentially transferredto the heating section 30 depends on the difference in transfer timingand the temperature decrease gradient θ2. Since the difference intransfer timing and the temperature decrease gradient θ2 are small, thedifference between the temperatures TE1, TE2, and TE3 of the preforms isrelatively small.

The difference between the temperatures TE1, TE2, and TE3 of thepreforms sequentially transferred to the heating section 30 can thus bereduced due to the synergistic effects (i.e., a reduction in temperaturedecrease gradient and a reduction in difference in timing of transfer tothe heating section) of forced cooling in the cooling section 20 andcontinuous transfer in the heating section 30. Note that the continuousheating period T3 according to one embodiment of the invention is longerthan the intermittent heating period T2 of Comparative Example 1 sincethe heating start temperature is low.

Note that the difference between the temperatures TE1, TE2, and TE3 ofthe preforms can be reduced as compared with Comparative Example 1 evenwhen implementing only one of forced cooling in the cooling section 20and continuous transfer in the heating section 30. Therefore, the blowmolding quality can be improved as compared with Comparative Example 1by continuously transferring the preforms in the heating section 30 evenif the cooling section 20 is not used, or the preforms are subjected tonatural cooling in the cooling section 20 without using the refrigerant.

In Comparative Example 2, since the preforms at room temperature aretransferred to the heating section, the difference between the performtemperatures TD1, TD2, and TD3 when the preforms are transferred to theheating section is small as compared with one embodiment of theinvention and Comparative Example 1. In Comparative Example 2, however,since the heating period T4 increases to a large extent in order to heatthe preforms from room temperature to the optimum blow temperature,energy consumption and the total length of the heating path inevitablyincrease.

According to one embodiment of the invention, the ill effect of heatthat is applied during injection molding and retained by the preforms onthe perform temperature during the n blow molding operations can bereduced by subjecting the N preforms transferred from the injectionmolding section 10 to forced cooling in the cooling section 20. Whensubjecting the preforms to forced cooling, the difference in temperaturebetween the N preforms before heating decreases as compared with thecase where the preforms are not subjected to forced cooling (i.e.,subjected to natural cooling). Since it is not necessary to cool thepreforms to room temperature by forced cooling, heat that is appliedduring injection molding and retained by the preforms can be used forblow molding.

The blow molding characteristics have a close relationship with theperform temperature. Specifically, the perform is easily stretched whenthe perform temperature is high, and is stretched with difficulty whenthe perform temperature is low. Therefore, a difference in performtemperature occurs when using the 1.5-stage method in which preformssimultaneously produced by injection molding are separately subjected toblow molding. According to one embodiment of the invention, thetemperature difference ΔT (see FIG. 10) can be significantly reduced ascompared with the temperature difference Δt of the comparative example.This makes it possible to suppress a variation in blow molding quality.

Although only some embodiments of the invention have been described indetail above, those skilled in the art would readily appreciate thatmany modifications are possible in the embodiments without materiallydeparting from the novel teachings and advantages of the invention.Accordingly, all such modifications are intended to be included withinthe scope of the invention. Any term cited with a different term havinga broader meaning or the same meaning at least once in the specificationand the drawings can be replaced by the different term in any place inthe specification and the drawings.

7. Modification of Removal Device 120

A configuration that is added to the configuration disclosed in JapanesePatent No. 4148576 as the removal device 120 illustrated in FIGS. 1 and2 is described below with reference to FIGS. 12 to 14B. The removaldevice 120 includes two rail main bodies 120A that move between theinjection molding section 10 and a position outside the injectionmolding section 10, and three (i.e., a plurality of) rows of pot supportstages 123A to 123C that support the pots 122 on the two rail mainbodies 120A so that the pitch can be changed. The center pot supportstage 123A is secured on the rail main body 120A, and the pot supportstages 123B and 123C provided on either side of the pot support stage123A can move relative to the rail main body 120A. Each of the potsupport stages 123A to 123C has a pot support hole 124, and a suctionport 124A is formed in the pot support hole 124.

A suction passage 125 (125A, 125B) that communicates with the suctionport 124 is provided in the center pot support stage 123A illustrated inFIG. 13A and the pot support stages 123B and 123C illustrated in FIG.13B that are provided on either side of the pot support stage 123A. Asillustrated in FIG. 13A, the suction passage 125A of the fixed potsupport stage 123A is open on each end, and always communicates with asuction passage 126 provided in the rail main body 120A. As illustratedin FIG. 13B, the suction passages 125B of the movable pot support stages123B and 123C are open on a side surface 125C, and communicate withsuction passages 128 provided in two connection sections 127 thatconnect the two rail main bodies 120A.

Two the air cylinders 129A and 129B (pitch change driving section 129)are supported by one of the connection sections 127. The rod of the aircylinder 129A is secured on the movable pot support stage 123B via ahole 123A1 formed in the fixed pot support stage 123A. The rod of theair cylinder 129B is secured on the movable pot support stage 123C.

FIG. 14A illustrates a wide pitch state. In this case, the suctionpassages 125B of the movable pot support stages 123B and 123Ccommunicate with the suction passages 128 provided in the two connectionsections 127. The pitch state is set to the wide pitch state whenreceiving the preforms in the injection molding section 10, and thepreforms can be sucked into and supported by the pots 122 (see FIGS. 1and 2) which are themselves supported by the pot support stages 123A to123C.

FIG. 14B illustrates a narrow pitch state. In this case, the suctionpassages 125B of the movable pot support stages 123B and 123C do notcommunicate with the suction passages 128 provided in the two connectionsections 127. The pitch state is set to the narrow pitch state after theremoval device 120 has reached the transfer position (see FIG. 2)outside the injection molding section 10, or before the removal device120 reaches the transfer position. It is necessary to cancel the suctionstate at the transfer position (see FIG. 2) for transferring thepreforms. Since communication with the suction passages 128 is canceledwhen the pitch state is set to the narrow pitch state, the suction stateis automatically canceled. The preforms cannot be sucked when thesuction passages 125B of the movable pot support stages 123B and 123C donot communicate with the suction passages 128 provided in the twoconnection sections 127. Note that it suffices to suck the preforms onlywhen receiving the preforms in the injection molding section 10. Thefixed pot support stage 123A tends to remain affected by the suctionstate for a long time as compared with the movable pot support stages123B and 123C. Therefore, an air supply circuit may be separatelyprovided to communicate with the fixed pot support stage 123A, andseparation of the preforms 2 and the fixed pot support stage 123A may bepromoted by supplying air when the pitch state is set to the narrowpitch state.

8. Modification of Perform Transfer Device 50

A modification of the perform transfer device 50 illustrated in FIGS. 3Aand 3B is described below with reference to FIGS. 15A to 16B. A baseboard 530 illustrated in FIGS. 15A and 15B is moved vertically andhorizontally by the first air cylinder 510 and the second air cylinder520 illustrated in FIG. 2. A stationary plate 531 and a movable plate532 are supported by the base board 530. A perform holder 540illustrated in FIGS. 16A and 16B is supported by the stationary plate531 and the movable plate 532 instead of the perform holder 500illustrated in FIGS. 3A and 3B.

The interval between the stationary plate 531 and the movable plate 532is changed by an air cylinder 533 (gap change driving section) between awide gap G1 illustrated in FIG. 15A and a narrow gap G2 illustrated inFIG. 15B.

The wide gap G1 illustrated in FIG. 15A is required due to the layout ofthe resin outlet of the hot runner mold in the injection molding section10. The arrangement pitch of three (n=3) rows of eight (M=8) preformssupported by the stationary plate 531 and the movable plate 532 is notconstant when the wide gap G1 is formed. The interval between thestationary plate 531 and the movable plate 532 is changed from the widegap G1 illustrated in FIG. 15A to the narrow gap G2 illustrated in FIG.15B before the perform transfer device 50 transfers the preforms to thecooling section 50 so that the arrangement pitch of three (n=3) rows ofeight (M=8) preforms supported by the stationary plate 531 and themovable plate 532 is made constant. Therefore, the perform arrangementpitch can be made constant in the cooling section 20, the heatingsection 30, and the blow molding section 40. Since the preforms arecontinuously transferred in the heating section 30, it is important tocontinuously transfer the preforms at a constant arrangement pitch sothat the effect of the adjacent preforms is constant. When the preformshave a large diameter (e.g., M=4), the arrangement pitch may be madeconstant by increasing the gap.

The perform holder 540 illustrated in FIGS. 16A and 16B is supported bythe stationary plate 531 and the movable plate 532 illustrated in FIGS.15A and 15B instead of the perform holder 500 illustrated in FIGS. 3Aand 3B. The perform holder 540 includes a holder main body 541, a core542 that is secured on the holder main body 541, and a top side sealmember 543 that is movable relative to the holder main body 541.

A suction passage 531A (532A) is formed in the stationary plate 531(movable plate 532). The suction passage 531A(532A) communicates withthe neck 2A of the perform 2 via the holder main body 541 and the core542.

The top side seal member 543 is supported so that the top side sealmember 543 can move upward and downward relative to the holder main body541. The top side seal member 543 is always biased downward by acompression coil spring 544 (i.e., biasing member).

The perform holder 540 is disposed over the perform 2 supported by thepot 122 of the removal device 120. When the perform holder 540 is moveddownward by the first air cylinder 510 (see FIG. 2), the core 542 isinserted into the neck 2A of the perform 2, and the top side of the neck2A is sealed by the top side seal member 543. An impact applied uponcontact with the top side seal member 543 is reduced, and the top sideseal member 543 maintain its top side seal capability due to thecompression coil spring 544.

The perform 2 is then sucked toward the perform holder 540, and theperform 2 supported by the pot 122 of the removal device 120 istransferred to the perform holder 540. The suction state is canceledwhen the perform holder 540 has transferred the perform 2 to the coolingsection 20, and the perform 2 is transferred to the cooling pot 220 (seeFIG. 4).

9. Modification of Cooling Section

A modification of the cooling section 20 is described below withreference to FIGS. 17 to 20. The cooling section 20 illustrated in FIG.17 includes the inversion section 200 that rotates around the rotaryshaft 204 in the same manner as in FIG. 4. Cooling pots 210A to 210Cthat cool a perform having a different size (see FIGS. 18A to 18C) canbe mounted on the cooling section 20 illustrated in FIG. 17.

As illustrated in FIG. 19, a small diameter hole 250A and a largediameter hole 250B are formed in the inversion section 200 as the potinsertion holes. Four (M/2=4) large diameter holes 250B are formed ineach of three rows (n=3) at a pitch P. Four (M/2=4) small diameter holes250A and four (M/2=4) large diameter holes 250B are alternately formedin each of the three rows (n=3). The arrangement pitch between the smalldiameter hole 250A and the large diameter hole 250B is P/2.

When producing the perform 2 having a large diameter illustrated in FIG.18A, the number of preforms simultaneously produced by injection moldingin the injection molding section 10 is reduced to N/2. In this case, N/2cooling pots 210A can be disposed on the first side 201 and the secondside 202 by disposing the cooling pot 210A illustrated in FIG. 18B inM/2 large diameter holes (n rows) formed in the inversion section 200.

Since it is possible to simultaneously produce N preforms having a smalldiameter (see FIG. 18B or 18C), N cooling pots 210B or 210C can bedisposed on the first side 201 and the second side 202 using M/2 smalldiameter holes 250A and M/2 large diameter holes 250B. When a coolingpot having an identical size is used for a perform having a smalldiameter, a space formed when inserting the cooling pot 210B or 210C(see FIG. 18B or 18C) into the large diameter hole 250B may be filledwith a lining material or the like.

Note that the cooling pot 210A inserted into the large diameter hole250B of the inversion section 200 is secured on the inversion section200 using a pot securing plate 260A (see FIG. 20A), and the smalldiameter hole 250A is closed. Note that the cooling pot 210B or 210Cinserted into the small diameter hole 250A of the inversion section 200is secured on the inversion section 200 using a pot securing plate 260B(see FIG. 20B), and the large diameter hole 250B is closed.

As illustrated in FIGS. 18A to 18C, a recess 211 is formed in the outerwall of the cooling pots 210A to 210C. In FIGS. 18A to 18C, two recesses11 are formed in the outer wall of the cooling pots 210A to 210C in thecircumferential direction. Note that only one recess 211 may be formed.

The inversion section 200 includes refrigerant (e.g., cold water) flowpassages 230A to 230D. The flow passages 230A and 230B that extend inthe horizontal direction communicate with the two recesses 11 of thecooling pots 210A to 210C to circulate the refrigerant. The recess 11thus forms part of the refrigerant flow passage.

The cooling efficiency can be improved by bringing the refrigerant intodirect contact with the outer wall of the cooling pots 210A to 210C overa wide area. The cooling pots 210A to 210C are selectively useddepending on the size of the perform. The inversion section 200 in whichthe flow passages 230A to 230D are formed can be used in common bymerely forming the recess 211 in the outer wall of the cooling pots 210Ato 210C.

10. Inversion Transfer Device on Downstream Side of Heating Section 30

An inversion transfer mechanism 70 that transfers the perform 2 in theinversion direction F illustrated in FIG. 2 or the inversion direction16 illustrated in FIG. 9, and the upward direction D illustrated in FIG.2, and transfers the perform 2 to the intermission transfer mechanism400 illustrated in FIG. 1 is described below with reference to FIGS. 21to 23.

As illustrated in FIGS. 21 to 23, the inversion transfer mechanism 70includes an elevating section 710 that moves together with an elevatingplate 702 that moves upward and downward along a guide shaft 700 via alinear bearing 701. The elevating plate 702 includes a nut section 713that engages a ball screw 712 that is driven by a servomotor 711 (i.e.,elevating driving section).

The elevating section 710 supports M pairs of chucks 720A and M pairs ofchucks 720B so that the M pairs of chucks 720A and the M pairs of chucks720B can be simultaneously opened and closed by upper and lower aircylinders 730A and 730B (i.e., opening/closing driving sections) (seeFIG. 22). The air cylinder 730A illustrated in FIG. 22 opens and closesthe chucks 720A and 720B positioned on the left side in FIG. 22, and theair cylinder 730B illustrated in FIG. 22 opens and closes the chucks720A and 720B positioned on the right side in FIG. 22 (only the chuck720B is illustrated in FIG. 22).

The M pairs of chucks 720A and the M pairs of chucks 720B are rotatedaround a rotary shaft 731 together with the rotary shaft 731. A slottedpulley 732 is secured on the rotary shaft 731. A timing belt 735 isfitted around a slotted pulley 734 that is rotated by a servomotor 733(i.e., rotation driving section) and a slotted pulley 732 that issecured on the rotary shaft 731.

When the elevating section 710 is situated at a lower position, the Mpairs of chucks 720B are closed to hold M preforms in the inverted statethat have been heated by the heating section 30. The elevating section710 is then moved upward, and the M pairs of chucks 720A and the M pairsof chucks 720B are rotated around the rotary shaft 731. Therefore, the Mpairs of chucks 720B are positioned on the upper side, and the preforms2 inverted from the inverted state to the upright state (see the arrowindicated by F in FIG. 2).

11. Blow Molding Section and Intermittent Transfer Mechanism

FIG. 24 illustrates a specific example of the blow molding section 40and the intermittent transfer mechanism 400. FIG. 25 is a front viewillustrating the blow molding section 40. The intermittent transfermechanism 400 is configured so that a carry-in section 410 and acarry-out section 420 are integrally reciprocated in the seconddirection D2 in FIG. 24. The carry-in section 410 and the carry-outsection 420 are reciprocated using two pinion gears 431 that are securedon the rotary shaft of a servomotor 430 (i.e., reciprocation drivingsection), and two racks 432 that engages the pinion gears 431 and aredriven linearly (partially illustrated in FIG. 24). The carry-in section410 and the carry-out section 420 are reciprocated integrally with theracks 432. The carry-in section 410 is reciprocated between aperform-receiving position P1 and a blow molding position P2, and thecarry-out section 420 is reciprocated between the blow molding positionP2 and an ejection position P3. Note that the carry-in section 410 isstopped at the perform-receiving position P1 or the blow moldingposition P2.

The carry-in section 410 includes M transfer members 411 that transfer Mpreforms. Each of the M transfer members 411 includes a pair of chucks412. The carry-out section 420 includes a transfer member 421 thatincludes a pair of chucks 422 that transfer M containers. The chucks 412and 422 are integrally opened and closed by transmitting a driving forceof four (i.e., a plurality of) air cylinders 440 (opening/closingdriving sections) via a link mechanism 441 (see FIG. 24).

As illustrated in FIG. 25, M preforms 2 are transferred by the Mtransfer members 411 of the carry-in section 410 to the blow moldingposition P2 of the blow molding section 40 in the directionperpendicular to the sheet. A blow cavity mold 41 has been opened. Theblow cavity mold 41, a blow core mold (not illustrated in FIG. 24), andan optional bottom mold are then clamped. The M preforms 2 are thustransferred to the blow molding section 40. The chucks 412 of the Mtransfer members 411 are opened, and moved from the blow moldingposition P2 to the perform-receiving position P1 (see FIG. 24). Thecarry-out section 420 is moved from the ejection position P3 to the blowmolding position P2, and held at the blow molding position P2 in a statein which the chucks 422 are opened.

When M containers have been molded from the M preforms 2 in the blowmolding section 40, the chucks 422 of the carry-out section 420 areclosed to hold the neck of each container. The chucks 412 of thecarry-in section 410 are closed at the perform-receiving position P1 tohold M preforms 2. The carry-out section 420 transfers the M containersfrom the blow molding position P2 to the ejection position P3, and thecarry-in section 410 moves the M preforms 2 from the perform-receivingposition P1 to the blow molding position P2. The blow molding section 40continuously implements the blow molding operation by repeating theabove operation.

An operation that transfers the perform 2 from the inversion transfermechanism 70 illustrated in FIGS. 21 to 23 to the carry-in section 410of the intermittent transfer mechanism 400 illustrated in FIG. 24 isdescribed below with reference to FIGS. 26 and 27.

T0 to T4 illustrated in FIGS. 26 and 27 are timings that change on thetime axis. FIGS. 26 and 27 illustrate the operations of a pair of chucks720A (hereinafter referred to as “a pair of first chucks”) and a pair ofchucks 412 (hereinafter referred to as “a pair of second chucks”) on thetime axis (from T0 to T4). These operations are performed at the performtransfer position P1 illustrated in FIG. 24.

At the timing T0, the perform 2 held by the pair of first chucks 720Astands by under the pair of second chucks 412 in an open state. At thetiming T1, the perform 2 held by the pair of first chucks 720A is movedupward, and the neck is disposed between the pair of second chucks 412in an open state.

At the timing T2, the pair of second chucks 412 in an open state isclosed. Therefore, the neck of the perform 2 is held by the pair offirst chucks 720A and the pair of second chucks 412 at the timing T2.

At the timing T3, the pair of first chucks 720A is moved downward. Theperform 2 is thus transferred from the pair of first chucks 720A to thepair of second chucks 412.

The pair of second chucks 412 is then transferred from theperform-receiving position P1 to the blow molding position P2. The pairof first chucks 720A is then moved downward, and rotated by theservomotor 733 (see FIG. 21), and the first chucks 720B that hold Mpreforms 2 are set to the position at the timing T0 in FIGS. 26 and 27.The pair of second chucks 412 is returned from the blow molding positionP1 to the perform transfer position P1, and set to the position at thetiming T0 in FIGS. 26 and 27. The above perform transfer operation isrepeated.

Although only some embodiments of the present invention have beendescribed in detail above, those skilled in the art will readilyappreciate that many modifications are possible in the embodimentswithout materially departing from the novel teachings and advantages ofthis invention. Accordingly, all such modifications are intended to beincluded within scope of this invention.

Although the invention has been described using specific terms, devices,and/or methods, such description is for illustrative purposes of thepreferred embodiment(s) only. Changes may be made to the preferredembodiment(s) by those of ordinary skill in the art without departingfrom the scope of the present invention, which is set forth in thefollowing claims. In addition, it should be understood that aspects ofthe preferred embodiment(s) generally may be interchanged in whole or inpart.

What is claimed is:
 1. A preform transfer device that transfers aplurality of preforms that have been produced by injection moldingperformed in an injection molding station to a subsequent station, thepreform transfer device comprising: a base board that is reciprocatedbetween a receiving position at which the plurality of preforms arereceived, and a position at which the plurality of preforms aretransferred; a stationary plate that is secured on the base board; amovable plate that is movably provided to the base board, the movableplate being disposed adjacently to the stationary plate in an identicalhorizontal plane so that a gap between the movable plate and thestationary plate can be changed; a plurality of preform holders that areprovided to the stationary plate and the movable plate, and respectivelyhold the plurality of preforms; and a gap change driving section thatchanges the gap so that a first gap when the plurality of preforms arereceived differs from a second gap when the plurality of preforms aretransferred.
 2. The preform transfer device as defined in claim 1, thegap change driving section changing the gap so that an arrangement pitchof the preform holders along a moving direction of the movable plate isconstant when the plurality of preforms are transferred.
 3. The preformtransfer device as defined in claim 2, the gap change driving sectionchanging the gap so that the second gap is narrower than the first gap.4. The preform transfer device as defined in claim 2, the gap changedriving section changing the gap so that the second gap is wider thanthe first gap.
 5. The preform transfer device as defined in claim 1, theplurality of preform holders including: a holder main body that issecured on the stationary plate or the movable plate; a core that issecured on the holder main body, and inserted into a neck of thepreform; and a top side seal member that is supported so that the topside seal member can move upward and downward relative to the holdermain body, and biased by a biasing member to seal a top side of the neckof the preform.
 6. The preform transfer device as defined in claim 5, asuction passage being formed in the stationary plate, the movable plate,the holder main body, and the core, the suction passage communicatingwith the neck of the perform.